The paranasal sinuses are air-filled regions within bones of the skull. Specifically, the frontal, ethmoid, maxilla, and sphenoid bones contain sinuses that are named for the bone structure that immediately surrounds them. In addition, the nasal region contains smaller bones including the inferior turbinate, lacrimal, palatine, and nasal bones. The spaces between these articulated bones are sometimes air filled. The bones of the sinus and nasal cavities are covered by a mucosa lining, producing mucus that drains into the nasal cavity and subsequently into the throat. A sinus cell is connected to the nasal cavity by a narrow opening called the ostium. The arrangement of sinus cells and bones forms paths for drainage. When drainage is prevented by constriction or blockage of the ostia and/or paths, sinusitis, infection or inflammation in the paranasal sinus region, can result.
The condition of the paranasal sinuses and nasal cavity can be assessed using an X-ray computerized tomographic (CT) image of a patient's head, at the level of the sinuses. Image acquisition for this purpose is generally performed with a fan-beam computed tomographic system (FBCT) or a conebeam computed tomographic (CBCT) system. However, the anatomy of the paranasal sinuses is very complicated, making it difficult to interpret images of the paranasal region and to detect problem conditions. As a further complication, the anatomy of the sinuses and bones of the nasal region can vary significantly from patient to patient. Furthermore, pathological conditions can greatly alter the anatomy of the sinuses and nasal cavity. For these reasons, it can be difficult even for a skilled practitioner to determine the condition and drainage paths for each sinus by examination of the axial, coronal, sagittal, and other views of the CT image.
Thus, there is a need for apparatus and methods for analysis and display of the paranasal sinus region, including nasal cavity structures, and for display of related drainage path information.